The present invention relates to a magnetic recording and reproducing apparatus for reading information from and writing information into a magnetic disk, and more particularly to a disk presser mechanism for pressing and positioning a magnetic disk on a base.
When a magnetic disk is loaded in a magnetic recording and reproducing apparatus, a magnetic head is moved into confronting relation to a read/write region on the disk, and a pad is brought into abutment against a side of the read/write region to press and position the disk against a reference surface of a base of the apparatus body. Ths disk is thus vertically set with respect to the head, and a liner (generally made of nonwoven fabric) on an inner surface of a disk case is pressed under suitable pressure against the magnetic medium stored in the disk case to effect self-cleaning on the magnetic medium rotating in the disk case.
A conventional pad presser mechanism is attached by a leaf spring to a turning clamp arm having a clamp member on a turntable. After the disk has been loaded, the clamp arm is lowered to clamp the disk on the turntable, whereupon the pad is pressed against the disk. Alternatively, a drive lever is provided for lowering the clamp arm. When the clamp arm is pushed in a clamping direction by the drive lever pressed by an actuator cam, the drive lever simultaneously operates the pad to cause the latter to press the disk.
However, the conventional disk presser mechanism has been disadvantageous in that the force with which the clamp arm and the drive lever are lowered affects and makes irregular the force with which the pad presses the disk. As a result, the force with which the disk is pressed by the pad may be too weak to position the disk accurately, or the magnetic medium cannot be sufficiently cleaned by the liner on the inner surface of the disk case. If the disk were pressed by the pad too strongly, frictional forces generated between the inner surface of the disk case and the magnetic medium would be increased to the extent that the magnetic medium would be worn quickly or the resistance to rotation of the magnetic medium in the disk case would be increased, requiring the turntable to produce an excessive drive force that would result in an increased electric power requirement.